1. Technical Field
This invention relates to a semiconductor light beam position sensor element and a position sensor and a picture image input device each using the same.
2. Background Technology
Japanese Patent Application KOKAI 50579/1984 discloses a semiconductor light beam position sensor element comprising a semiconductor layer composed of p-, i- and n-type semiconductors successively formed and a light-transparent electrically conductive layer disposed on either side of said semiconductor layer, said light-transparent electrically conductive layers having at least one pair of electrodes disposed in juxtaposition.
A light beam incident, at one point, on one of the transparent conductive layers of such a semiconductor light beam position sensor element passes through the particular transparent conductive layer to its semiconductor layer. In the semiconductor layer, the incidence of the light beam gives rise to electron-hole pairs within the i-type amorphous semiconductor and, of such a pair, the electron diffuses into the n-type amorphous semiconductor while the positive hole moves into the p-type amorphous semiconductor. As a result, an electromotive force is generated between the two transparent conductive layers. Therefore, when an ammeter is externally connected to each of the electrodes, the current derived from the electrodes can be measured. Since the current values thus measured are dependent on the distance between the point of incidence of the light beam and the respective electrodes, the point of incidence of the light beam can be found from the measured current values.
Since the conventional semiconductor light beam position sensor element described above employs amorphous semiconductors, the position sensor element with a large area can be easily obtained. But the light transparency of the whole element cannot be realized because of the low clarity of the semiconductor layer. Therefore, the semiconductor light beam position sensor element is limited in the range of application.
Having been accomplished to overcome the above disadvantage, this invention has, as its object, to provide a transparent semiconductor light beam position sensor element and a position sensor and a picture image input device utilizing the same.